During ophthalmic surgery in the posterior region, such as during vitreo-retinal surgical procedures, illuminating the surgical region is a high priority. The illuminators need to have a small diameter so that a small incision is sufficient for their insertion. At the same time, they need to emit the illumination light in as wide an angle as possible to illuminate the largest possible area. The angle of emission is controlled by the numerical aperture and thus the diameter of the fibers. In general, achieving wider emission angles necessitates thicker fibers. These two design criteria of small fiber diameters and large illumination angles are therefore in direct competition with each other, making achieving a good design optimum a genuine challenge.
Some existing illuminators increase the illumination angle by tapering the optical fiber to a smaller diameter towards the tip. Analyzing the light rays shows that such fiber optic illuminators can emit the light rays with larger angles compared to the angles the numerical aperture of the fiber would naturally support. The tapering of the fibers is typically performed thermally, mechanically, or chemically.
However, the performance of these tapered fiber illuminators turns out to be quite sensitive to manufacturing the fibers with precisely the right taper angle. Adhering to this low tolerance is a substantial manufacturing challenge. Further, achieving the higher angular divergence also poses tight design requirements on the refractive index of the fiber core and the cladding.
Other illuminators are fabricated by modifying the tip of the optical fiber by mechanical, irradiative or chemical processes. However, to preserve the integrity of the fibers during these often forceful fabrication steps, these fibers typically have to be encased in a manufacturing sheath, or jacket, for support. This requirement typically complicates the manufacturing and makes it more expensive.
Further, in today's surgical practice, the surgeon typically holds a phaco-tip in one hand and a vitreous cutter in the other, both entered into the eye via dedicated incisions. Therefore, an additional, highly trained nurse or junior medical professional is needed to hold the illuminator, inserted through a third incision. If the illuminator could be integrated with one of the other surgical devices, that could eliminate the need for a third hand, making the surgical procedure two-handed, or bi-manual, performable by the surgeon alone. Reducing the number of surgical professionals needed for these ophthalmic procedures would have numerous advantages.
Also, needing fewer incisions would reduce the deformation and structural weakening of the eye caused by the incisions of the ophthalmic surgery.
With today's illuminators it is not easy to satisfy the above needs, as they often use fibers that are thicker, such as having a fiber diameter in excess of 500 microns. Moreover, they often have a jacket, or sheath, for strength. If such a thick illuminator were somehow affixed to one of the other surgical devices, that would increase the diameter, or form factor, of that integrated device substantially, thus increasing the size of the incision necessary for its insertion, to undesirable levels.
Therefore, there is a need for illuminators that have small diameters, yet can emit illuminating light into a wide angle; do not require a sheath or jacket for their manufacture; and can be integrated with another surgical device without increasing the form factor of the device, thus also reducing the number of incisions necessary for the ophthalmic surgical procedure, as well as the number of hands and thus the number of professionals needed for ophthalmic surgery.